Washing Group for Laundry Washing Machines

ABSTRACT

A washing group ( 1 ) for laundry washing machines has a hollow washing tub ( 2 ), a revolving drum ( 3 ) fitted in axially rotatable manner inside the washing tub ( 2 ), and a motor assembly ( 4 ) which is rigidly attached outside the washing tub ( 2 ) and is capable of driving into rotation the revolving drum ( 3 ) inside the washing tub ( 2 ). The motor assembly ( 4 ) has a drive motor ( 8 ) and a supporting structure ( 10 ) provided with a number of connecting arms ( 15 ) each of which juts out from the drive motor ( 8 ) towards the peripheral wall ( 9 ) of washing tub ( 2 ), and has the distal end fitted onto a corresponding coupling pin ( 14 ) which cantilevered extends from the washing tub ( 2 ). Each coupling pin ( 14 ) is substantially ogival-shaped and the distal end of each connecting arm ( 15 ) having a substantially ogival-shaped, hollow seat ( 16 ) which is substantially complementary in shape to that of the corresponding coupling pin ( 14 ) so as to be axially engaged by said coupling pin ( 14 ).

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to European Application No. 15193109.4,filed Nov. 5, 2015, the content of which is hereby incorporated byreference in its entirety.

FIELD

The present invention relates to a washing group for laundry washingmachines. In particular, aspects of the present invention relate to awashing group for home laundry washing machines, to which the followingdescription refers purely by way of example without this implying anyloss of generality.

BACKGROUND

As is known, currently marketed home laundry washing machines generallycomprise: a substantially parallelepiped-shaped, outer boxlike casingstructured for resting on the floor; an approximately cylindrical,hollow washing tub which is usually arranged substantially horizontallyinside the casing and is provided with a laundry loading and unloadingmouth that directly faces a large pass-through opening which is formedeither in the top or in the front wall of the casing and is dimensionedfor allowing an easy manual loading and unloading of the laundry insidethe washing tub; a substantially cylindrical, hollow drum which isfitted in axially rotatable manner inside the washing tub and isstructured for accommodating the laundry to be washed; anelastically-deformable bellows which watertight connects the mouth ofthe washing tub to the pass-through opening formed in the top or frontwall of the casing; and a manually-operated door which is hinged to thetop or front wall of the casing so as to be able to rotate to and from aclosing position in which the door closes the pass-through opening forwatertight sealing the washing tub.

In addition to the above, currently marketed home laundry washingmachines comprise: an electric motor which is rigidly attached outsideand underneath the washing tub, and is mechanically connected to therotatable drum thus to be able to drive into rotation the drum insidethe washing tub; an electrically-operated, water and detergent supplyassembly which is structured for selectively feeding into the washingtub, according to the selected washing cycle, a given amount ofdetergent, softener and/or other washing agent suitably mixed with thefresh water arriving from the water mains, or simply a given amount offresh water arriving from the water mains; an electric heating devicelocated inside the washing tub and capable of selectively heating up thewater contained into the washing tub; and finally an electronic centralcontrol unit which controls the electric motor, the heating device andthe water and detergent supply assembly to selectively perform one ofthe user-selectable washing cycles stored in the same central controlunit.

To speed up the assembly of the household appliance, in today's homelaundry washing machines the washing tub, the rotatable drum, theheating device and the electric motor are generally assembled to oneanother on a separate assembly line so as to form a so-called washinggroup which is subsequently inserted into the outer casing of thelaundry washing machine.

EP2775024A1 discloses a washing group wherein the electric motor isfirmly enclosed between a pair of reciprocally-faced, cup-shapedend-shields which are arranged coaxial to the longitudinal axis of themotor, and each of which is provided with a pair of outwards-projectingconnecting arms structured for being rigidly fastened to the bottom ofthe washing tub.

More specifically, the distal end of each connecting arm protruding fromthe front end-shield, i.e. from the end-shield engaged in pass-throughand axially rotatable manner by the driving shaft of the electric motor,is provided with a transversal hollow seat which is frustoconical inshape and is dimensioned to be axially fitted onto a corresponding,complementary-shaped, frustoconical coupling pin which is integrallyformed on the bottom portion of the washing tub and extends outside ofthe washing tub coaxial to a reference axis parallel to the longitudinalaxis of the motor. An axial screw moreover fastens the distal end ofeach connecting arm to the corresponding frustoconical-shaped couplingpin.

The distal end of each connecting arm protruding from the rearend-shield, in turn, is provided with a transversal, pass-through holewhich is cylindrical in shape and is dimensioned to be axially fittedonto a corresponding, complementary-shaped cylindrical coupling pinwhich is integrally formed on the bottom portion of the washing tub andextends outside of the washing tub coaxial to a reference axis parallelto the longitudinal axis of the motor.

The two frustoconical-shaped coupling pins are used for centring themotor assembly on the fixing portion of the washing tub, whereas the twocylindrical-shaped coupling pins bears almost the whole weight of themotor assembly and support the mechanical stresses during operation ofthe electric motor.

Unfortunately, due to the considerable increase in rotation speed andtorque value produced by today's electric motors, the referred-abovefastening system is no more able to provide a sufficiently rigidcoupling between electric motor and washing tub, with all the problemsthat this entails.

Summary of Selected Inventive Aspects

An aim of the present invention is therefore to realize a much morerigid mechanical coupling between electric motor and washing tub, whichis moreover capable of speeding up the assembly of the electric motoronto the bottom portion of washing tub.

In compliance with the above aims, according to aspects of the presentinvention there is provided a washing group for laundry washing machinescomprising a hollow washing tub, a revolving drum fitted in axiallyrotatable manner inside the washing tub, and a motor assembly includinga drive motor which is rigidly attached outside the washing tub and iscapable of driving into rotation the revolving drum inside the washingtub;

-   -   the motor assembly also including at least one connecting part        having an end portion fitted onto a corresponding coupling pin        extending from the washing tub or vice versa;    -   the washing group being characterized in that each coupling pin        has a frustoconical-shaped distal portion and an adjacent,        cylindrical-shaped mid portion adjoining said        frustoconical-shaped distal portion; and in that the end portion        of the connecting part has a hollow seat which is substantially        complementary in shape to that of the corresponding coupling pin        so as to be axially engaged by said coupling pin.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that said cylindrical-shaped mid portion adjoins thefrustoconical-shaped distal portion to a proximal end of the couplingpin which is rigidly connected to the washing tub or to the drive motor;the proximal end of said coupling pin having, adjacent to saidcylindrical-shaped mid portion and opposite to the frustoconical-shapeddistal portion, a stop surface wherein the distal end of the connectingpart stably abuts.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the proximal end of said coupling pin is providedwith a substantially annular-shaped, stop shoulder which adjoins thecylindrical portion, and wherein the distal end of connecting partstably abuts.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the axial length of said frustoconical-shapeddistal portion is greater than the axial length of saidcylindrical-shaped mid portion.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the axial length of said cylindrical-shaped midportion is moreover approximately equal to half the axial length of saidfrustoconical-shaped distal portion.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the axial length of said frustoconical-shapeddistal portion ranges between 5 mm and 25 millimeters.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the axial length of said cylindrical-shaped midportion ranges between 5 mm and 15 millimeters.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the opening angle of said frustoconical-shapeddistal portion ranges between 20° and 60°.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the outer diameter of said cylindrical-shaped midportion ranges between 8 and 40 millimeters.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the motor assembly includes a number of connectingparts each having an end portion fitted onto a corresponding couplingpin extending from the washing tub or vice versa, and in that saidcoupling pins are substantially parallel to a common fitting direction.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the motor assembly includes a number of connectingparts each having an end portion fitted onto a corresponding couplingpin extending from the washing tub or vice versa, and in that allcoupling pins are identical in shape to one another and are preferablyfour in number.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that said revolving drum extends coaxial to alongitudinal axis of the washing tub, and in that said fitting directionis substantially parallel the longitudinal axis of said washing tub.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that said motor assembly moreover comprises at leastone fixing screw engaging in sequence the end portion of the connectingpart and the corresponding coupling pin.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that said fixing screw extends coaxial to said couplingpin.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the motor assembly includes a number of connectingparts each having an end portion fitted onto a corresponding couplingpin extending from the washing tub or vice versa, and in that said motorassembly comprises a fixing screw for each coupling pin.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the motor assembly additionally comprises asupporting structure which is provided with a number of connecting armseach of which juts out from the drive motor towards the peripheral wallof washing tub; the distal end of each connecting arm forming arespective end portion of the connecting part.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that said revolving drum extends coaxial to alongitudinal axis of the washing tub, and in that supporting structureis designed to arrange said drive motor with the longitudinal axis ofthe motor substantially parallel to the longitudinal axis of saidwashing tub.

Preferably, though not necessarily, the washing group is furthermorecharacterized in that the drive motor is an electric motor, and in thatsaid supporting structure comprises at least one substantiallycup-shaped, end-shield which is rigidly secured to an end-portion ofsaid electric motor, and is provided with a number ofoutwards-protruding, connecting arms which extend toward the couplingpins on the washing tub.

According to aspects of the present invention there is also provided awashing group for laundry washing machines comprising a hollow washingtub, a revolving drum fitted in axially rotatable manner inside thewashing tub, and a motor assembly which is rigidly attached outside thewashing tub and is capable of driving into rotation the revolving druminside the washing tub;

-   -   the motor assembly in turn comprising a drive motor and a        supporting structure provided with a number of connecting arms        each of which juts out from the drive motor towards the        peripheral wall of washing tub, and has the distal end fitted        onto a corresponding coupling pin which cantilevered extends        from the washing tub;    -   the washing group being characterized in that each coupling pin        has a frustoconical-shaped distal portion and an adjacent,        cylindrical-shaped mid portion adjoining said        frustoconical-shaped distal portion; and in that the distal end        of each connecting arm has a substantially ogival-shaped, hollow        seat which is substantially complementary in shape to that of        the corresponding coupling pin so as to be axially engaged by        said coupling pin.

Preferably, though not necessarily, the washing group is furthermorecharacterized in said cylindrical-shaped mid portion adjoins thefrustoconical-shaped distal portion to a proximal end of the couplingpin which is rigidly connected to the washing tub; the proximal end ofsaid coupling pin having, adjacent to said cylindrical-shaped midportion and opposite to the frustoconical-shaped distal portion, a stopsurface wherein the distal end of the connecting arm stably abuts.

Preferably, though not necessarily, the washing group is furthermorecharacterized in the proximal end of said coupling pin is provided witha substantially annular-shaped, stop shoulder which adjoins thecylindrical portion, and wherein the distal end of connecting arm stablyabuts.

According to aspects of the present invention there is also provided alaundry washing machine having an outer casing structured for resting onthe floor, and a washing group which is arranged inside the casing andcomprises a hollow washing tub, a revolving drum fitted in axiallyrotatable manner inside the washing tub, and a motor assembly which isrigidly attached outside the washing tub and is capable of driving intorotation the revolving drum inside the washing tub;

-   -   the laundry washing machine being characterized in that said        motor assembly includes a drive motor which is rigidly attached        outside the washing tub and is capable of driving into rotation        the revolving drum inside the washing tub, and also at least one        connecting part having an end portion fitted onto a        corresponding coupling pin extending from the washing tub or        vice versa; in that each coupling pin has a frustoconical-shaped        distal portion and an adjacent, cylindrical-shaped mid portion        adjoining said frustoconical-shaped distal portion; and in that        the end portion of the connecting part has a hollow seat which        is substantially complementary in shape to that of the        corresponding coupling pin so as to be axially engaged by said        coupling pin.

According to aspects of the present invention there is also provided alaundry washing machine having an outer casing structured for resting onthe floor, and a washing group which is arranged inside the casing andcomprises a hollow washing tub, a revolving drum fitted in axiallyrotatable manner inside the washing tub, and a motor assembly which isrigidly attached outside the washing tub and is capable of driving intorotation the revolving drum inside the washing tub;

-   -   the laundry washing machine being characterized in that said        motor assembly comprises a drive motor and a supporting        structure provided with a number of connecting arms each of        which juts out from the drive motor towards the peripheral wall        of washing tub, and has the distal end fitted onto a        corresponding coupling pin which cantilevered extends from the        washing tub; in that each coupling pin has a        frustoconical-shaped distal portion and an adjacent,        cylindrical-shaped mid portion adjoining said        frustoconical-shaped distal portion; and in that the distal end        of each connecting arm has a substantially ogival-shaped, hollow        seat which is substantially complementary in shape to that of        the corresponding coupling pin so as to be axially engaged by        said coupling pin.

BRIEF DESCRIPTION OF THE DRAWINGS

A non-limiting embodiment of the present invention will now bedescribed, by way of example, with reference to the accompanyingdrawings, in which:

FIG. 1 is a perspective view, with parts in section and parts removedfor clarity, of a front-loading laundry washing machine provided with awashing group realized in accordance with aspects of the presentinvention;

FIG. 2 is an enlarged perspective view of the washing group shown inFIG. 1 with parts in section and parts removed for clarity;

FIG. 3 is an exploded perspective view of the bottom portion of the FIG.2 washing group, with parts removed for clarity;

FIG. 4 is an enlarged side view of the bottom portion of the FIG. 2washing group, with parts in section and parts removed for clarity;whereas

FIG. 5 is an exploded side view of the coupling between the washing tuband the motor assembly of the FIG. 2 washing group, with parts insection and parts removed for clarity.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

With reference to FIGS. 1 and 2, reference number 1 indicates as a wholea washing group suitably structured/designed for being incorporated intoa laundry washing machine.

More in detail, a home laundry washing machine 100 basically comprises:a preferably, though not necessarily, substantiallyparallelepiped-shaped, outer boxlike casing 101 structured for restingon the floor; and a washing group 1 which is accommodated, preferablysubstantially horizontally, inside the casing 101.

In the example shown, in particular, the washing group 1 is preferablysuspended in floating manner inside the casing 101 via a suspensionsystem which preferably, though not necessarily, comprises at least oneand preferably a couple of upper coil springs 102 connecting the upperportion of washing group 1 to the top portion of boxlike casing 101, andpreferably at least one, and preferably a couple of vibration dampers103 connecting the bottom portion of washing group 1 to the bottomportion of boxlike casing 101.

The washing group 1 in turn comprises: a preferably substantiallycylindrical, hollow washing tub 2 which is structured for beingarranged, preferably substantially horizontally, inside the casing 101,and is provided with a laundry loading and unloading mouth (not visiblein the figures) which is dimensioned for allowing an easy loading andunloading of the laundry inside the washing tub 2; a substantiallycylindrical, hollow revolving drum 3 which is fitted in axiallyrotatable manner inside the washing tub 2 and is structured foraccommodating the laundry to be washed; and a motor assembly 4 which isrigidly attached outside and preferably underneath the washing tub 2,and is mechanically connected to the revolving drum 3 thus to be able todrive into rotation the same revolving drum 3 inside the washing tub 2.

More in detail, the revolving drum 3 extends inside the washing tub 2coaxial to a reference axis A preferably locally substantiallycoinciding with the preferably horizontally-oriented, longitudinalreference axis of washing tub 2, and is rigidly fixed to the inner axialend of a central supporting shaft 5 which extends coaxial to axis A andis fitted in pass-through and axially rotatable manner into the rearwall 6 of washing tub 2 so as to stick out from the back of washing tub2.

The washing group 1 preferably furthermore comprises a first pulley 7which is arranged outside of washing tub 2 coaxial to the longitudinalaxis A of revolving drum 3 and supporting shaft 5, and is rigidly fittedto the outer axial end of supporting shaft 5, so as to be able to rotateabout axis A together with revolving drum 3 and supporting shaft 5.

In the example shown, in particular, the washing group 1 is preferablystructured for being incorporated into a front-loading laundry washingmachine 100, therefore the preferably circular-shaped, laundry loadingand unloading mouth (not visible in the figures) of washing tub 2 ispreferably located roughly at centre of the front wall of washing tub 2,i.e. the wall opposite to rear wall 6, so as to directly face a largepass-through opening which is formed in the front wall of boxlike casing101 and is dimensioned for allowing an easy manual loading and unloadingof the laundry inside the washing tub 2.

The revolving drum 3, in turn, is preferably substantially cup-shapedand is fitted in axially rotatable manner inside the washing tub 2 withthe concavity facing the laundry loading and unloading mouth of washingtub 2, so as to receive the laundry to be washed.

With reference to FIGS. 2, 3, 4 and 5, the motor assembly 4 in turncomprises: a drive motor 8 which is capable of driving into rotation thesupporting shaft 5 of revolving drum 3 about longitudinal axis A, and isarranged beneath the washing tub 2, adjacent to a fixing arrangementformed on the substantially cylindrical-shaped, peripheral wall 9 ofwashing tub 2, with the motor longitudinal axis B locally substantiallyparallel to the longitudinal axis A of supporting shaft 5 and revolvingdrum 3; and preferably an intermediate supporting structure 10 whichrigidly connects the drive motor 8 to the peripheral wall 9 of washingtub 2.

More in detail, the supporting structure 10 is firmly secured to thedrive motor 8 and is structured/designed to be rigidly fitted andfastened to the fixing arrangement on peripheral wall 9, preferably ineasy detachable manner, so as to arrange, when firmly secured to washingtub 2, the longitudinal axis B of drive motor 8 substantially parallelto the longitudinal axis A of supporting shaft 5 and revolving drum 3.

In the example shown, in particular, the motor assembly 4 preferablycomprises a second pulley 11 which is arranged coaxial to longitudinalaxis B, and is rigidly fitted to the distal end of the driving shaft 12of drive motor 8; and the supporting structure 10 is preferably designedfor arranging, when firmly secured to the washing tub 2, the pulley 11substantially coplanar to pulley 7.

Preferably the washing group 1 furthermore comprises a driving belt 13which is looped over pulleys 7 and 11 thus to allow the drive motor 8 toselectively drive into rotation both supporting shaft 5 and revolvingdrum 3 about longitudinal axis A.

With reference to FIGS. 3, 4 and 5, the fixing arrangement of washingtub 2 basically comprises a number of locally reciprocally-parallel andsubstantially ogival-shaped, coupling pins 14 which are rigidly fixed tothe peripheral wall 9 of washing tub 2, and extend cantilevered outsideof washing tub 2 while remaining locally parallel to a same fittingdirection f which is preferably locally substantially parallel to thelongitudinal axis A of supporting shaft 5 and of revolving drum 3, i.e.to the longitudinal axis of washing tub 2.

In other words, each coupling pin 14 is located outside of washing tub2, has the proximal end stably connected to the peripheral wall 9 ofwashing tub 2, and finally extend cantilevered from washing tub 2coaxial to a longitudinal reference axis C which is locally parallel tothe fitting direction f and preferably also to the longitudinal axis Aof supporting shaft 5 and revolving drum 3.

Preferably the coupling pins 14 are moreover identical in shape to oneanother.

In the example shown, in particular, each coupling pin 14 of washing tub2 preferably cantilevered sticks out from a supporting appendage whichprotrudes from peripheral wall 9 and is preferably realized in one piecewith peripheral wall 9 of washing tub 2.

With reference to FIGS. 4 and 5, each coupling pin 14 of washing tub 2furthermore has a frustoconical-shaped distal portion 14 a extendingcoaxial to longitudinal axis C, and an adjacent cylindrical-shaped midportion 14 b extending coaxial to longitudinal axis C. Saidcylindrical-shaped mid portion 14 b adjoins the frustoconical-shapeddistal portion 14 a to the proximal end of coupling pin 14.

The proximal end of coupling pin 14 moreover has, immediately adjacentto the cylindrical-shaped mid portion 14 b and opposite to distalportion 14 a, a stop surface 14 c wherein the distal end of connectingarm 15 stably abuts.

More in detail, the proximal end of coupling pin 14 is preferablyprovided with a substantially annular-shaped, stop shoulder 14 c whichadjoins the cylindrical-shaped mid portion 14 b, and wherein the distalend of connecting arm 15 stably abuts.

In the example shown, furthermore, the axial length l_(a) offrustoconical-shaped portion 14 a is preferably greater than the axiallength l_(b) of cylindrical-shaped portion 14 b.

Preferably the axial length l_(b) of cylindrical-shaped portion 14 b ismoreover approximately equal to, or even greater than, half the axiallength l_(a) of the frustoconical-shaped portion 14 a.

More in detail, the axial length l_(a) of frustoconical-shaped portion14 a preferably ranges between 5 mm and 25 mm (millimeters), whereas theaxial length l_(b) of cylindrical-shaped portion 14 b preferably rangesbetween 5 mm and 15 mm (millimeters).

Preferably the opening angle α of the frustoconical-shaped portion 14 afurthermore ranges between 20° and 60°.

Preferably the outer diameter of cylindrical-shaped portion 14 bfurthermore ranges between 8 mm and 40 mm (millimeters).

With reference to FIGS. 2, 3, 4 and 5, the supporting structure 10 inturn comprises a number of connecting arms 15 each of which juts outfrom drive motor 8 and extends towards the fixing arrangement onperipheral wall 9, so as to reach and rigidly couple to a correspondingcoupling pin 14 of washing tub 2.

More in detail, the distal end of each connecting arm 15 is providedwith a substantially ogival-shaped, hollow seat 16 which issubstantially complementary in shape to that of the coupling pins 14 soas to accommodate a coupling pin 14, and extends coaxial to alongitudinal reference axis D which is locally substantially parallel tothe fitting direction f and preferably also to the longitudinal axis Bof drive motor 8, so as to be axially engaged by said coupling pin 14.

In other words, the hollow seat 16 on the distal end of each connectingarm 15 is designed to have a frustoconical-shaped bottom portion 16 awhich extends coaxial to longitudinal axis D and is substantiallycomplementary-shaped to the distal portion 14 a of coupling pin 14; andan adjacent cylindrical portion 16 b which extends coaxial to axis D foradjoining the frustoconical-shaped bottom portion 16 a to the mouth ofhollow seat 16, and is substantially complementary-shaped to the midportion 14 b of coupling pin 14, so that the distal end of connectingarm 15 can stably abut onto the stop shoulder 14 c of coupling pin 14when the coupling pin 14 is completely fitted into the ogival-shapedhollow seat 16.

Obviously when fitted into the hollow seat 16, the coupling pin 14 iscoaxial to the longitudinal axis D of same hollow seat 16.

In the example shown, in particular, the connecting arms 15 arepreferably located at both axial ends of drive motor 8, and furthermoreextend towards the fixing arrangement on peripheral wall 9 preferablywhile remaining locally substantially perpendicular to the peripheralwall 9 and/or to the fitting direction f, and preferably also whileremaining substantially perpendicular to longitudinal axis B of drivemotor 8.

With reference to FIGS. 2, 3, 4 and 5, in more general terms the motorassembly 4 includes at least one connecting part 15 which has an endportion 16 fitted onto a corresponding substantially ogival-shaped,coupling pin 14 extending from the washing tub 2.

Preferably, with reference to FIGS. 3, 4 and 5, the motor assembly 4additionally comprises, preferably for each coupling pin 14 of washingtub 2, a fixing screw 17 which engages in sequence the distal end ofconnecting arm 15 and the corresponding coupling pin 14, thus to firmlyhold the distal end of connecting arm 15 in stable abutment against thestop shoulder 14 c at the proximal end of coupling pin 14.

More in detail, fixing screw 17 preferably extends coaxial to thelongitudinal axis C of coupling pin 14 so as to place the head 17 a offixing screw 17 in abutment on the distal end of connecting arm 15,opposite to the ogival-shaped hollow seat 16. The threaded shank 17 b offixing screw 17, in turn, firstly engages the distal end of connectingarm 15 thus to protrude into the ogival-shaped hollow seat 16 formed onsaid distal end, and then engages the coupling pin 14 preferably inpass-through manner, so as to firmly secure the two components inabutment to one another.

With reference to FIGS. 4 and 5, in particular, each coupling pin 14 ispreferably provided with a through hole 18 extending coaxial tolongitudinal axis C, and the tip portion of threaded shank 17 b isscrewed into said through hole 18. The distal end of connecting arm 15,in turn, is preferably provided, opposite to the mouth of hollow seat16, with a through hole 19 that adjoins to the bottom of hollow seat 16,and the neck of fixing screw 17 engages said through hole 19.

As an alternative the coupling pin 14 could centrally incorporate astiffening insert and the threaded shank 17 b of fixing screw 17 screwsinto said stiffening insert, or the threaded shank 17 b of fixing screw17 could extend along the through hole 18 for the whole length ofcoupling pin 14 and screw into a lock nut arranged beyond the proximalend of the coupling pin 14.

With reference to FIG. 3, in the example shown, in particular, thefixing arrangement on the peripheral wall 9 of washing tub 2 preferablycomprises four reciprocally-parallel coupling pins 14, and preferably afixing screw 17 for each coupling pin 14.

Preferably sais coupling pins 14 are furthermore arranged in pairsparallel and spaced beside to one another. Preferably the pairs ofcoupling pins 14 are moreover aligned to one another parallel to fittingdirection f, so to form two adjacent and reciprocally-parallel rows ofcoupling pins 14 on peripheral wall 9 of washing tub 2.

With reference to FIGS. 2, 3 and 4, in the example shown, furthermore,the drive motor 8 is preferably an electric motor, such as for example aasynchronous motor or a commutator electric motor.

The supporting structure 10, in turn, preferably comprises a pair ofpreferably substantially cup-shaped, end-shields 20 and 21 which arearranged on opposite sides of drive motor 8, roughly coaxial to thelongitudinal axis B, and are rigidly secured respectively to the frontand rear portions of electric motor 8 preferably via a number of fixingbolts or other fastening members.

The front end-shield 20, i.e. the end-shield engaged in pass-through andaxially rotatable manner by the driving shaft 12 of drive motor 8, ispreferably provided with two substantially coplanar andoutwards-protruding, connecting arms 15 which extend toward a first pairof coupling pins 14 of washing tub 2. Each connecting arm 15 ofend-shield 20 furthermore has a substantially cup-shaped, distal endwhich is designed to fit onto a respective coupling pin 14 of said firstpair of coupling pins 14.

In other words, the central cavity of the cup-shaped, distal end ofconnecting arm 15 forms the substantially ogival-shaped, hollow seat 16which is axially engaged by the coupling pin 14.

Similarly to front end-shield 20, the rear end-shield 21 is providedwith two substantially coplanar outwards-protruding, connecting arms 15which extend toward a second pair of coupling pins 14 of washing tub 2.Each connecting arm 15 of end-shield 21 furthermore has a substantiallycup-shaped, distal end which is designed to fit onto a respectivecoupling pin 14 of said second pair of coupling pins 14.

With reference to FIGS. 1 and 2, preferably the washing group 1 finallycomprises also an electric heating device 22, for example a resistor,which is fixed to washing tub 2 so as to at least partially protrudeinside washing tub 2, and is capable of selectively heating up the watercontained into the washing tub 2.

Preferably the laundry washing machine 100 moreover comprises: anelectrically-operated, water and detergent supply assembly 104 which ispreferably located immediately above the washing group 1, and isstructured for selectively feeding into the washing tub 2 a given amountof detergent, softener and/or other washing agent suitably mixed withthe fresh water arriving from the water mains, or simply a given amountof fresh water arriving from the water mains; and an electronic centralcontrol unit (not shown) which controls the electric motor 8, theheating device 22 and the water and detergent supply assembly 104 toselectively perform one of the user-selectable washing cycles stored inthe same central control unit.

General operation of washing group 1 is clearly inferable from the abovedescription, with no further explanation required.

The advantages deriving from the particular structure of coupling pins14 and of the distal ends of connecting arms 15 are large in number.

Having both a frustoconical-shaped distal portion 14 a and an adjacentcylindrical-shaped mid portion 14 b, each coupling pin 14 can operate asa centring member during assembly of supporting structure 10 on washingtub 2, and at same time can directly bear the weight of motor assembly 4even when fixing screws 17 are missing. Therefore the assembly ofsupporting structure 10 to washing tub 2 is significantly quicker.

Moreover, the presence of the stop shoulder 14 c adjacent to thecylindrical-shaped portion 14 b, improves stiffness of the mechanicalcoupling between the coupling pin 14 and the distal end of theconnecting arm 15. The distal end of connecting arm 15, in fact, is nowtighten between the stop shoulder 14 c and the head 17 a of fixing screw17.

Furthermore being now arranged at vertex of a quadrilateral, thecylindrical-shaped mid portions 14 b offers a much more stable supportfor motor assembly 4 during working of drive motor 8.

Last but not least, since each coupling pins 14 has a cylindrical-shapedmid portion 14 b, the overall contact surface capable of bearing themechanical stresses during working of drive motor 8 is significantlyincreased with respect to the fixing system disclosed in EP2775024A1,with all advantages that this entails.

Clearly, changes may be made to both washing group 1 and laundry washingmachine 100 described above without, however, departing from the scopeof the present invention.

For example, the coupling pins 14 may be located on the distal end ofthe connecting arms 15 whereas the hollow seats 16 may be integrallyformed on the peripheral wall 9 of washing tub 2.

In other words, the motor assembly 4 may include one or moreogival-shaped, coupling pin 14 extending from the drive motor 8 andfitted into corresponding connecting part/s 15 formed on washing tub 2.

Furthermore the supporting structure 10 may solely comprise the frontend-shield 20 with the corresponding connecting arms 15.

In other words, the supporting structure 10 may comprise a number ofconnecting arms 15 which juts out solely from the front portion ofelectric motor 8 towards a number of corresponding coupling pins 14located on the peripheral wall 9 of washing tub 2.

1. A washing group for laundry washing machines comprising a hollowwashing tub, a revolving drum fitted in axially rotatable manner insidethe washing tub, and a motor assembly including a drive motor which isrigidly attached outside the washing tub and is capable of driving intorotation the revolving drum inside the washing tub; the motor assemblyalso including at least one connecting part having an end portion fittedonto a corresponding coupling pin extending from the washing tub or viceversa; wherein each coupling pin has a frustoconical-shaped distalportion and an adjacent, cylindrical-shaped mid portion adjoining saidfrustoconical-shaped distal portion; and the end portion of theconnecting part has a hollow seat which is substantially complementaryin shape to that of the corresponding coupling pin so as to be axiallyengaged by said coupling pin.
 2. The washing group according to claim 1,wherein said cylindrical-shaped mid portion adjoins thefrustoconical-shaped distal portion to a proximal end of the couplingpin which is rigidly connected to the washing tub or to the drive motor;the proximal end of said coupling pin having, adjacent to saidcylindrical-shaped mid portion and opposite to the frustoconical-shapeddistal portion, a stop surface wherein the distal end of the connectingpart stably abuts.
 3. The washing group according to claim 2, whereinthe proximal end of said coupling pin is provided with a substantiallyannular-shaped, stop shoulder which adjoins the cylindrical portion, andwherein the distal end of connecting part stably abuts.
 4. The washinggroup according to claim 1, wherein the axial length (l_(a)) of saidfrustoconical-shaped distal portion is greater than the axial length(l_(b)) of said cylindrical-shaped mid portion.
 5. The washing groupaccording to claim 4, wherein the axial length (l_(b)) of saidcylindrical-shaped mid portion is moreover approximately equal to halfthe axial length (l_(a)) of said frustoconical-shaped distal portion. 6.The washing group according to claim 1, wherein the opening angle (a) ofsaid frustoconical-shaped distal portion ranges between 20° and 60°. 7.The washing group according to claim 1, wherein the outer diameter ofsaid cylindrical-shaped mid portion ranges between 8 and 40 millimeters.8. The washing group according to claim 1, wherein the motor assemblyincludes a number of connecting parts each having an end portion fittedonto a corresponding coupling pin extending from the washing tub or viceversa, and in that said coupling pins are substantially parallel to acommon fitting direction (f).
 9. The washing group according to claim 1,wherein the motor assembly includes a number of connecting parts eachhaving an end portion fitted onto a corresponding coupling pin extendingfrom the washing tub or vice versa, and in that all coupling pins areidentical in shape to one another and are preferably four in number. 10.The washing group according to claim 8, wherein said revolving drumextends coaxial to a longitudinal axis (A) of the washing tub, and inthat said fitting direction (f) is substantially parallel thelongitudinal axis (A) of said washing tub.
 11. The washing groupaccording to claim 1, wherein said motor assembly moreover comprises atleast one fixing screw engaging in sequence the end portion of theconnecting part and the corresponding coupling pin.
 12. The washinggroup according to claim 11, wherein said fixing screw extends coaxialto said coupling pin.
 13. The washing group according to claim 11,wherein the motor assembly includes a number of connecting parts eachhaving an end portion fitted onto a corresponding coupling pin extendingfrom the washing tub or vice versa, and in that said motor assemblycomprises a fixing screw for each coupling pin.
 14. The washing groupaccording to claim 1, wherein the motor assembly additionally comprisesa supporting structure which is provided with a number of connectingarms each of which juts out from the drive motor towards the peripheralwall of washing tub; the distal end of each connecting arm forming arespective end portion of the connecting part.
 15. A laundry washingmachine having an outer casing structured for resting on the floor, anda washing group which is arranged inside the casing and comprises ahollow washing tub, a revolving drum fitted in axially rotatable mannerinside the washing tub, and a motor assembly which is rigidly attachedoutside the washing tub and is capable of driving into rotation therevolving drum inside the washing tub; wherein said washing group is awashing group according to claim 1.